Case IH 520228-19 - VCM – VCM: Steering valve controller communication fault with the wheel angle sensor (WAS)

The steering valve controller is not receiving the expected CAN bus messages from the wheel angle sensor, either due to a boot-up timeout, an abnormal update rate, or a complete loss of connection.

• MAGNUM AFS Connect
• Magnum
• Steiger
• Puma
• Maxxum
• Optum
• Patriot 3230
• Patriot 3320
• Patriot 3330
• Patriot 4420
• Patriot 4430
• Trident 5550

1. 1

   Verify Power and Ground: Check that the Wheel Angle Sensor is receiving proper power and ground. A loss of power to the sensor will immediately trigger a missing message fault.

2. 2

   Inspect the CAN Bus: Check the CAN bus wiring harness connecting the WAS to the steering valve controller. Look for disconnected plugs, chafed wires, or loose pins.

3. 3

   Check Battery Voltage: Low battery voltage is a common cause of CAN communication dropouts in Case IH equipment. Ensure the battery is maintaining above 11.5 volts during operation.

4. 4

   Inspect Physical Linkage: Verify that the mechanical linkage connecting the wheel angle sensor to the steering axle is intact and has not been damaged or over-extended.

1. 1

   Power Down

   Turn off the tractor/sprayer and disconnect the battery to prevent electrical shorts during inspection.

2. 2

   Harness Repair

   If the diagnostic checks reveal damaged wiring between the WAS and the steering valve controller, repair or replace the affected harness section.

3. 3

   Sensor Replacement

   If the wiring is intact and the sensor is receiving power but not broadcasting CAN messages, the internal circuitry of the WAS has likely failed. Unbolt the sensor linkage, disconnect the harness, and replace the Wheel Angle Sensor.

4. 4

   Reassembly

   Install the new sensor, ensuring the ball mounts and jam nuts are securely fastened to the steering linkage. Reconnect the battery.

5. 5

   Mandatory Calibration

   Perform a Wheel Angle Sensor and Steering Valve calibration after replacing the sensor or repairing the circuit. Turn on the tractor and initialize the external guidance system/display, navigate to the ISObus diagnostic page or steering settings, and follow the on-screen prompts to calibrate the left, right, and center steering limits.